Spinnability window

Those involved in dry spinning of acrylics refer to a spinnability window, i.e. the conditions required to produce a fiber of the right quality. As noted in the preceding section, polymer solution viscosity and temperature are key factors. A polymer solution viscosity that is too high or too low can lead to broken filaments, as can too high a polymer solution temperature. As also noted earlier, the rate of evaporation of the solvent is another key factor. If evaporation is too rapid, vapor bubbles can form in the filaments, reducing filament strength (Cox, 2005). 

The fibrillation of LCPs in thermoplastic melts is influenced by several parameters, including the thermal characteristics of the component polymers and their compatibility, and processing parameters such as viscosity ratio, melt temperature, flow mode, and shear rate. Among these parameters, thermal characteristics of LCPs are basic factors for the formation of LCP fibrils. They should have the matched processing window with the matrix resin, when the former is in the liquid crystal state. It has been found that the spinnability of LCPs can be taken as a prerequisite for the accomplishment of submicrometer reinforcing with LCP fibrils [18]. 

The effect of aging time was also mentioned by Alio et al. [140], who qualitatively observed a continuous increment in solution viscosity during electrospinning of a sol containing TEOS and PCL, which highlighted the importance of finding the proper window of operation for spinnability. 

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